Removed interface, not using it anymore.

Also simplified a line of code in user.can() method
Added 'created' and 'modified' fields to Object (and so all models)
Moved Group, User and Permission to ufcommon.auth.model
Updated packages and imports to reflect new location
Changed from array to list to fit with CompileTime.getAllClasses()
Only import the relationship manager if on the server
Added Auth Plan